| 1 | Latin | exercitus | occupied, exercised, practised; vexed, harassed;... |
| 2 | Latin | exerceo | I keep busy, keep at work, drive on; occupy,... |
| 3 | Latin | arceo | I shut up, enclose; box in; I keep off, ward off;... |
| 4 | Proto-Italic | arkeō | — |
| 5 | Proto-Indo-European | h₂erk- | to protect, guard, hold, lock |